Method and apparatus for SIP message prioritization

ABSTRACT

The invention includes a method and apparatus for providing SIP message prioritization between network elements along at least a portion of an end-to-end path between a SIP client and a SIP server. The method includes determining a SIP message prioritization policy and distributing the SIP message prioritization policy toward a prioritizing network element adapted to assign message priority levels to respective received SIP messages using the SIP message prioritization policy, process the received SIP messages according to the respective assigned message priority levels, and transmit the prioritized SIP messages toward at least one network element in a manner for propagating the respective assigned message priority levels to the at least one network element. The prioritizing network elements include SIP network elements and non-SIP network elements.

FIELD OF THE INVENTION

The invention relates to the field of communication networks and, morespecifically, to Session Initiation Protocol based communicationnetworks.

BACKGROUND OF THE INVENTION

The Internet Protocol (IP) Multimedia Subsystem (IMS) architecture isevolving as the service infrastructure for IP networks. The IMSarchitecture supports services such as voice-over-IP (VoIP), multimediasessions, presence, instant messaging, gaming, and various otherservices. The Session Initiation Protocol (SIP) is an important part ofthe IMS architecture. In support of such services, SIP messages arerouted between SIP network elements (including SIP end user equipment)according to the SIP protocol as defined in RFC3261, RFC3263, andassociated extension documents. In a SIP network, equipment thatinitiates a SIP message is referred to as a SIP client (e.g., SIP UserAgent Client) and the equipment that terminates a SIP message isreferred to as a SIP server (e.g., SIP User Agent Server).

The SIP messages transmitted between SIP clients and SIP serverstraverse SIP network elements supporting various functions. For example,SIP message transmitted between SIP UACs and SIP UASs may traverse SIPproxy servers that determine the next SIP element in the routing path,SIP registrars that register SIP device locations in databases, SIPapplication servers that perform application specific operations basedon SIP message content, and various other SIP network elements. Sincethe IMS architecture supports a variety of different services, SIPmessages may differ in their importance or urgency (e.g., the set of SIPmessages required for establishing an E-911 emergency call may have ahigher importance and urgency than respective sets of SIP messagesrequired for establishing standard VoIP calls).

In general, the number of SIP messages in a SIP network elementrepresents the load of the SIP network element. A high-load conditionoccurs if a SIP network element receives more messages than it iscapable of processing. Several measures are available to deal withhigh-load conditions. For example, SIP network element hardwareequipment may be upgraded, or load distribution strategies may beapplied in order to divide SIP messages across several SIP networkelements. Disadvantageously, however, despite careful networkengineering, SIP network elements may experience high-load and overloadconditions, thereby resulting in SIP message delays and dropsindependent of the importance or urgency of the SIP messages.

SUMMARY OF THE INVENTION

Various deficiencies in the prior art are addressed through theinvention of a method and apparatus for providing SIP messageprioritization between network elements along at least a portion of anend-to-end path between a SIP client and a SIP server. The methodincludes determining a SIP message prioritization policy anddistributing the SIP message prioritization policy toward a prioritizingnetwork element adapted to assign message priority levels to respectivereceived SIP messages using the SIP message prioritization policy,process the received SIP messages according to the respective assignedmessage priority levels, and transmit the prioritized SIP messagestoward at least one network element in a manner for propagating therespective assigned message priority levels to the at least one networkelement. The prioritizing network elements include SIP network elementsand non-SIP network elements.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a high-level block diagram of a communication network;

FIG. 2 depicts a method according to one embodiment of the presentinvention;

FIG. 3 depicts a high-level block diagram of a prioritizing SIP networkelement;

FIG. 4 depicts a method according to one embodiment of the presentinvention;

FIG. 5 depicts a high-level block diagram of a prioritizationarchitecture from the perspective of a plurality of prioritizing SIPnetwork elements using associated SIP message prioritization policiesfor prioritizing SIP messages and processing SIP messages using messagepriority levels of the prioritized SIP messages; and

FIG. 6 depicts a high-level block diagram of a general-purpose computersuitable for use in performing the functions described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides prioritization of SIP messages on atleast a portion of an end-to-end path (i.e., across SIP networkelements). The prioritization of SIP messages across SIP networkelements may be performed using a prioritization policy determined anddistributed to the SIP network elements by a management system. Theprioritization policy may be determined based on information fromnetwork (including feedback from prioritizing SIP network elementsutilizing the prioritization policy). The message priority levelsassigned according to the prioritization policy may be used to processthe prioritized SIP messages to perform various functions, includingselecting output networks, selecting quality of service parameters,selecting next SIP network elements, processing SIP messages within SIPnetwork elements according to the message priority levels, and the like,as well as various combinations thereof. The prioritizing SIP networkelements may propagate (convey) message priority levels between networkelements.

The present invention provides prioritization of SIP messages within aprioritizing SIP network element. A prioritizing SIP network elementincludes a first SIP message parsing and prioritization stage in which aportion of each SIP message is parsed in order to determine and assignan associated message priority level. The prioritization of SIP messages(i.e., determining the message priority level assigned to each SIPmessage) may be performed using a SIP message prioritization policy. Theassignment of the determined message priority level may be performedusing at least one of a plurality of message priority level assignmentmethods. A prioritizing SIP network element includes a second SIPmessage parsing and processing stage in which remaining portions of eachSIP message (e.g., portions not parsed by the first stage) are parsedand processed in order to process the message (e.g., route the SIPmessage, perform an application-specific function in response to the SIPmessage, and the like). The processing of prioritized SIP messages isperformed using respective assigned message priority levels.

FIG. 1 depicts a high-level block diagram of a communication network.Specifically, communication network 100 includes a pair of SIP useragents (UAs), illustratively, a client SIP UA 102 _(C) (denoted as SIPUAC 102 _(C)) and a server SIP UA 102 _(S) (denoted as SIP UAS 102 _(S))in communication using a respective pair of external IP networks 104_(C) and 104 _(S) (collectively, external IP networks 104) and a serviceprovider domain 101. As depicted in FIG. 1, external IP networks 104access service provider domain 101 using a respective pair of routers.As depicted in FIG. 1, communication network 100 includes aprioritization policy management system (PPMS) 160 adapted fordetermining, applying, and controlling prioritization policies withinservice provider domain 101. The communication network 100 uses SIPsignaling to support services such as voice-over-IP sessions, multimediasessions, presence, instant messaging, gaming, and the like.

As depicted in FIG. 1, service provider domain 101 includes a pluralityof IP networks 110 ₁, 110 _(2A)-110 _(2C) (collectively, IP networks 110₂), 110 _(3A)-110 _(3C), (collectively, IP networks 110 ₃), and 110 ₄.The IP networks 110 ₁-110 ₄ may be collectively referred to herein as IPnetworks 110. As depicted in FIG. 1, IP networks 110 include packetnetworks operable for transporting messages having varying messagepriority levels. In one embodiment, at least a portion of IP networks110 may be adapted to support prioritized SIP messages (illustratively,IP networks 110 ₂ and 110 ₃ support prioritized SIP messages). Asdepicted in FIG. 1, IP networks 110 ₂ support priority level one(denoted as P₁) and priority level two (denoted as P₂) and IP networks110 ₃ support priority level three (denoted as P₃) and priority levelfour (denoted as P₄).

As depicted in FIG. 1, service provider domain 101 includes a pluralityof routers 120 ₁-120 ₄ (collectively, routers 120). The routers 120include network elements operable for routing messages between networkcomponents. The routers 120 are adapted for processing messages havingvarying message priority levels. In one embodiment, at least a portionof routers 120 may be adapted to support prioritized SIP messages. Inone embodiment, at least a portion of routers 120 may be adapted toapply QOS parameters to prioritized SIP messages according to messagepriority level. As depicted in FIG. 1, router 120 ₂ supports prioritylevels one and two (P₁ and P₂), router 120 ₃ supports priority levelsthree and four (P₃ and P₄), and router 120 ₄ supports priority levelsone, two, three, and four (P₁, P₂, P₃, and P₄).

As depicted in FIG. 1, service provider domain 101 includes a pluralityof prioritizing SIP proxies (PSPs) 130 ₁-130 ₃ (collectively, PSPs 130).The PSPs 130 include network elements operable for determining the nextSIP network element in the SIP message routing path. The PSPs 130 areadapted for processing messages having varying message priority levels.In one embodiment, at least a portion of PSPs 130 may be adapted toperform initial prioritization of SIP messages to one of a plurality ofmessage priority levels, reprioritization of SIP messages from onemessage priority level to another message priority level, and likemessage prioritization functions. As depicted in FIG. 1, PSP 130 ₁supports priority levels one, two, three, and four (P₁, P₂, P₃, and P₄),PSP 130 ₂ supports priority levels one and two (P₁ and P₂), and PSP 130₃ supports priority levels three and four (P₃ and P₄).

As depicted in FIG. 1, service provider domain 101 includes a pluralityof prioritizing SIP application servers (PSASs) 140 ₁-140 ₂(collectively, PSASs 140). The routers 120 include network elementsoperable for performing various application specific operations based onSIP message content. The PSASs 140 include network elements operable forprocessing messages having varying message priority levels. In oneembodiment, at least a portion of PSASs 130 may be adapted to performinitial prioritization of SIP messages to one of a plurality of messagepriority levels, reprioritization of SIP messages from one messagepriority level to another message priority level, and like messageprioritization functions. As depicted in FIG. 1, PSAS 140 ₁ supportspriority levels one and two (P₁ and P₂), and PSAS 140 ₂ supportspriority levels three and four (P₃ and P₄).

The SIP UAC 102 _(C) and external IP network 104 _(C) communicate usinga link 103 _(C). The external IP network 104 _(C) and router 120 ₁communicate using a link 105 _(C). The SIP UAS 102 _(S) and external IPnetwork 104 _(s) communicate using a link 103 _(S). The external IPnetwork 104 _(s) and router 120 ₄ communicate using a link 105 _(S). Therouter 120 ₁ and IP network 110 ₁ communicate using a link 111. The IPnetwork 110 ₁ and PSP 130 ₁ communicate using a link 113. The PSP 130 ₁communicates with router 120 ₄ using one of a pair of communicationpaths adapted for transporting SIP messages having different messagepriority levels (illustratively, one path supports SIP messages havingpriority levels one and two and the other path supports SIP messageshaving priority levels three and four).

With respect to the path supporting SIP messages having priority levelsone and two, PSP 130 ₁ communicates, from an associated port 132 ₁₋₁₂,with IP network 110 _(2A) using a link 115 ₁. The IP network 110 _(2A)communicates with ports 142 ₁₋₁ (for SIP messages having priority levelone) and 142 ₁₋₂ (for SIP messages having priority level two) of PSAS140 ₁ using links 117 ₁₋₁ and 117 ₁₋₂, respectively. The IP network 110_(2A) communicates with router 120 ₂ using a link 119 ₁. The router 120₂ communicates with IP network 110 _(2B) using a link 121 ₁. The IPnetwork 110 _(2B) communicates with ports 132 ₂₋₁ (for SIP messageshaving priority level one) and 132 ₂₋₂ (for SIP messages having prioritylevel two) of PSP 130 ₂ using links 123 ₁₋₁ and 123 ₁₋₂, respectively.The PSP 130 ₂ communicates with IP network 110 _(2C) using link 125 ₁.The IP network 110 _(2C) communicates with router 120 ₄ using link 127₁.

With respect to the path supporting SIP messages having priority levelsthree and four, PSP 130 ₁ communicates, from an associated port 132₁₋₃₄, with IP network 110 _(3A) using a link 115 ₂. The IP network 110_(3A) communicates with ports 142 ₂₋₃ (for SIP messages having prioritylevel three) and 142 ₂₋₄ (for SIP messages having priority level four)of PSAS 140 ₂ using links 117 ₂₋₃ and 117 ₂₋₄, respectively. The IPnetwork 110 _(3A) communicates with router 120 ₃ using a link 119 ₂. Therouter 120 ₃ communicates with IP network 110 _(3B) using a link 121 ₂.The IP network 110 _(3B) communicates with ports 132 ₃₋₃ (for SIPmessages having priority level three) and 132 ₃₋₄ (for SIP messageshaving priority level four) of PSP 130 ₃ using links 123 ₂₋₃ and 123₂₋₄, respectively. The PSP 130 ₃ communicates with IP network 110 _(3C)using link 125 ₂. The IP network 110 _(3C) communicates with router 120₄ using link 127 ₂.

As depicted in FIG. 1, PSPs 130 and PSASs 140 operate as prioritizingSIP network elements, and routers 120 ₂, 120 ₃ and 120 ₄ operate asprioritizing non-SIP network elements. The prioritizing SIP networkelements and prioritizing non-SIP network elements may be collectivelyreferred to as prioritizing network elements. The remaining networkcomponents depicted and described with respect to FIG. 1 (e.g., SIP UAC102 _(C), router 120 ₁, SIP UAS 102 _(S), and the like) operate asnon-prioritizing network components, including both non-prioritizing SIPnetwork elements and non-prioritizing non-SIP network elements.

As depicted in FIG. 1, PPMS 160 determines message prioritizationpolicies adapted for supporting message prioritization along at least aportion of an end-to-end communication path. The PPMS 160 determines SIPmessage prioritization policies adapted for coordinating SIP messageprioritization across various network components of a service providerdomain (illustratively, routers 120 ₂ and 120 ₃, PSPs 130, and PSASs 140of service provider domain 101). The PPMS 160 determines SIP messageprioritization policies adapted for supporting multiple message prioritylevels. In one embodiment, SIP message prioritization policies may bedetermined and generated manually by one or more operators using PPMS160. In one embodiment, SIP message prioritization policies may bedetermined and generated automatically by PPMS 160. Although depicted asa standalone system, in one embodiment, at least a portion of thefunctions depicted and described herein with respect to PPMS 160 may beco-located with one or more network elements.

As described herein, PPMS 160 may determine and generate SIP messageprioritization policies using various combinations of information. Inone embodiment, PPMS 160 may determine and generate SIP messageprioritization policies using information obtained from other managementsystems (e.g., information associated with scheduled events which mayresult in changes in network traffic patterns, network traffic volumes,and the like, as well as various combinations thereof). In oneembodiment, PPMS 160 may determine and generate SIP messageprioritization policies using information obtained from the network,such as monitored and measured network traffic message characteristics,network traffic load conditions, and the like, as well as variouscombinations thereof. In one embodiment, PPMS 160 may determine andgenerate SIP message prioritization policies using various combinationsof other information described herein.

The PPMS 160 distributes SIP message prioritization policies to networkelements in service provider domain 101. As depicted in FIG. 1, PPMS 160distributes SIP message prioritization policies to routers 120 ₂ and 120₃, PSPs 130, and PSASs 140 to configure routers 120 ₂ and 120 ₃, PSPs130, and PSASs 140 to support varying SIP message priority levels. Asdepicted in FIG. 1, PPMS 160 distributes at least one prioritizationpolicy to each of PSP 130 ₁, PSAS 140 ₁, router 120 ₂, PSP 130 ₂, androuter 120 ₄ for supporting SIP messages having priority levels one andtwo. As depicted in FIG. 1, PPMS 160 distributes at least oneprioritization policy to each of PSP 130 ₁, PSAS 140 ₂, router 120 ₃,PSP 130 ₃, and router 120 ₄ for supporting SIP messages having prioritylevels three and four. The routers 120 ₂ and 120 ₃, PSPs 130, and PSASs140 use the SIP message prioritization policies to assign messagepriority levels to SIP messages for use in processing the prioritizedSIP messages.

As depicted in FIG. 1, PPMS 160 communicates with various networkcomponents of service provider domain 101 using router 120 ₅. The PPMS160 communicates with service provider domain 101 using a link 161.Although not specifically depicted, router 120 ₅ may communicate,directly or indirectly, with various combinations of network componentsof service provider domain 101. For example, in one embodiment, router120 ₅ may communicate with router 120 ₁ using IP network 110 ₄ andassociated links 163 and 165. For example, in one embodiment, router 120₅ may communicate with IP network 110 _(3B) using a link 167. Althoughnot depicted, in an embodiment in which prioritization functionalitydescribed with respect to PPMS 160 is implemented as a portion of one ormore network components of service provider domain 101, communicationsassociated with such prioritization functionality may be conveyed by thenetwork components of service provider domain 101.

In one embodiment, initial determination of a message priority level fora SIP message may be performed by one of a plurality of SIP componentsalong the end-to-end path between SIP UAC and SIP UAS (e.g., SIP UAC,SIP proxy servers, SIP application servers, and the like). As depictedin FIG. 1, PSP 130 ₁ performs the initial determination and assignmentof a message priority level to each SIP message initiated by SIP UAC 102_(C) that is intended for SIP UAS 102 _(S). In one embodiment, a messagepriority level initially determined and assigned to a SIP message may bemodified by one or more of a plurality of SIP components between the SIPcomponent which initially determined and assigned the message prioritylevel and the SIP UAS (e.g., SIP proxy servers, SIP application servers,and the like).

In one embodiment, determination of a message priority level of a SIPmessage (either initial determination or subsequent determination) maybe performed using one or more SIP message prioritization policies. Inone such embodiment, determination of a message priority level of a SIPmessage may be based on one or more SIP message prioritization factorsassociated with the one or more SIP message prioritization policies(e.g., factors used by the SIP message prioritization policy todetermine message priority levels of SIP messages). As such, since, inone embodiment, similar processing may be performed for determining aninitial message priority level of a SIP message or determining asubsequent message priority level of a SIP message, unless otherwisenoted, any function/capability/means/method described herein withrespect to determining a message priority level may be utilized forinitially or subsequently (if a message priority level was assigned byanother prioritizing SIP network element) determining a message prioritylevel of a SIP message.

In one embodiment, the message priority level of the SIP message isdetermined using the SIP message prioritization policy and the at leastone parameter. In one embodiment, in response to a determination that amessage priority level of SIP message was not previously assigned to theSIP message, a portion of a SIP message header of the received SIPmessage may be parsed in order to identify the at least one parameteradapted for use in determining the message priority level. In oneembodiment, in response to a determination that the message prioritylevel of SIP message was previously assigned to the SIP message, aportion of a SIP message header of the received SIP message may beparsed in order to determine the previously assigned message prioritylevel of the SIP message. In one such embodiment, the previouslyassigned message priority level may constitute one of the identifiedparameters used in conjunction with a SIP message prioritization policyto determine and assign the message priority level to the SIP message.

In one embodiment, a message priority level of a SIP message may bedetermined based on at least one of at least one SIP messagecharacteristic (e.g., SIP message type, SIP message size, and the like,as well as various combinations thereof), at least one SIP messageheader field (including respective SIP message header field names andSIP message header field values), SIP message content, and the like, aswell as various combinations thereof. In one embodiment, a messagepriority level may be assigned or modified based on the transaction type(e.g., the SIP dialog or transaction to which the SIP message belongs).In one embodiment, a message priority level of a SIP message may bedetermined based on traffic measurements (e.g., network and networkelement traffic load measurements, and the like, as well as variouscombinations thereof). In one embodiment, a message priority level of aSIP message may be determined based on time (e.g., day of year, day ofweek, time of day, and the like) as well as various combinationsthereof.

In one embodiment, a message priority level of a SIP message may bedetermined based on at least one network transport layer characteristic(e.g., IP source address, IP destination address, port number, transportprotocol type (e.g., Transmission Control Protocol (TCP), User DatagramProtocol (UDP), and the like), and the like, as well as variouscombinations thereof). In one embodiment, a message priority level of aSIP message may be determined based on at least one network data linklayer characteristic (e.g., retransmission counters). Although describedwith respect to network transport and data link layer characteristics,in one embodiment, a message priority level of a SIP message may bedetermined based on various other network characteristics, protocolcharacteristics, and the like, as well as various combinations thereof.

As depicted in FIG. 1, each SIP message received by PSP 130 ₁ from SIPUAC 102 _(C) is assigned a message priority level (e.g., includingmessage priority levels one (P₁), two (P₂), three (P₃), and four (P₄)),where P₁>P₂>P₃>P₄. In one embodiment, in which the received SIP messagedoes not have an associated message priority level, PSP 130 ₁ processesthe SIP message for determining and assigning a message priority level.The processing of received SIP messages for determining, assigning, andutilizing (internally) a message priority level is depicted anddescribed herein with respect to FIG. 3-FIG. 4. In one embodiment, inwhich the message priority level of a received SIP message waspreviously established (e.g., established at SIP UAC 102 _(C) uponformation of the SIP message), PSP 130 ₁ processes the prioritized SIPmessage for determining the previously assigned message priority level.

The prioritizing SIP network element which assigns message prioritylevels to respective SIP messages assigns message priority levels in amanner for enabling propagation of message priority levels to otherprioritizing SIP network elements. In one embodiment, message prioritylevels may be propagated between network elements in a manner preventingother prioritizing SIP network elements from having to re-determine themessage priority levels in the manner required by the initial SIPnetwork element which assigned respective message priority levels (e.g.,the SIP message prioritization policy may indicate that the previouslyassigned message priority level be retained). The propagation of messagepriority levels to other prioritizing network elements (prioritizing SIPnetwork elements, prioritizing non-SIP network elements, and the like,as well as various combinations thereof) associated with the end-to-endpath between SIP UAC and SIP UAS may be performed using various messagepriority level propagation schemes.

In one embodiment, message priority levels may be propagated by mappingthe port on which the SIP message is received to a message prioritylevel. In one embodiment, message priority levels may be propagated bymodifying a portion of an existing message header to convey the messagepriority level. In one embodiment, message priority levels may bepropagated by adding a new message header to convey the message prioritylevel (e.g., the Resource-Priority header). In one embodiment, messagepriority levels may be propagated by mapping respective portions of IPheaders of IP messages (e.g., TOS bytes of respective IP messageheaders) transporting a SIP message to an associated message prioritylevel. In one embodiment, message priority levels may be propagated byusing different SIP network elements, including prioritizing SIP networkelements and non-prioritizing SIP network elements, for differentmessage priority levels, and the like.

The processing of a prioritized SIP message to determine a previouslyassigned message priority level associated with the SIP message may beperformed in various manners. In one embodiment, the message prioritylevel of a SIP message may be determined using at least one header field(e.g., a SIP header field, an IP header field, an additional headerfield, and the like). In one embodiment, the message priority level maybe determined based on the network component from which the SIP messageis received (e.g., from a network, from a network element, and thelike). In one embodiment, the message priority level may be determinedbased on the port on which the SIP message is received. Althoughdescribed with respect to PSP 130 ₁, each prioritizing network componentof service provider domain 101 may perform such processing, either basedon other network elements or independent of other network elements, inorder to determine the message priority level of a prioritized SIPmessage.

In one embodiment, prioritized SIP messages may be processed in amessage processing order determined according to the respective messagepriority levels. In one embodiment, prioritized SIP message may beprocessed using the respective message priority levels. In oneembodiment, processing of prioritized SIP messages using respectivemessage priority levels of the SIP messages may be performed using oneor more prioritization policies (e.g., prioritization policiesdistributed by PPMS 160). The processing of prioritized SIP messagesusing respective message priority levels of the SIP messages may varyacross network components (e.g., processing of SIP messages byprioritizing SIP proxies and prioritizing SIP application servers isdifferent).

In one embodiment, prioritizing SIP network elements (e.g., PSPs,routers, PSASs, and the like) may process prioritized SIP messages fordetermining routing of the prioritized SIP messages. In one embodiment,prioritizing SIP network elements may process prioritized SIP messagesfor selecting a next prioritizing SIP network element to which eachprioritized SIP message is transmitted. In one embodiment, selection ofthe next prioritizing SIP network element to which a prioritized SIPmessage is transmitted may be based on the associated message prioritylevel. In one embodiment, selection of the next prioritizing SIP networkelement to which a prioritized SIP message is transmitted may be basedon functional capabilities of respective prioritizing SIP networkelements available for selection as the next prioritizing SIP networkelement.

In one embodiment (e.g., in which prioritizing SIP network elementsavailable for selection as the next prioritizing SIP network element aresubstantially similar with respect to functional capabilities, as wellas SIP message protocol) selection of the next prioritizing SIP networkelement to which a prioritized SIP message is transmitted may be basedon non-functional capabilities (e.g., processing capacity, processingspeed, quality of service parameters, reliability, and the like, as wellas various combinations thereof) of the prioritizing SIP networkelements available for selection. For example, emergency high-prioritySIP messages (e.g., E-911) may be routed to a dedicated, high speed,highly reliable prioritizing SIP network element in order to minimizethe delay of the emergency, high-priority SIP messages, while normal SIPmessages are routed to one or more other prioritizing SIP networkelements having lower speed, reliability, and like parameters.

In one embodiment, in which a plurality of output network connectionsare available for transmitting SIP messages from a current prioritizingSIP network element to a selected next prioritizing SIP network element,the current prioritizing SIP network element may select betweenavailable output network connections using various combinations ofoutput network connection selection factors. The available outputnetwork connections may provide paths alternative paths to the sameprioritizing SIP network element, or, alternatively, to differentprioritizing SIP network elements. The output network selection factorsmay include at least one of message priority levels of prioritized SIPmessages, properties of the available output networks, and the like, aswell as various combinations thereof.

In one embodiment, selection between available output networkconnections may be based on static properties of the respectiveavailable output networks. In one embodiment, static propertiesconsidered for selecting between available output network connectionsmay include available bandwidth (e.g., average, maximum, minimumguaranteed, and the like), network reliability, distance (e.g., numberof hops) to next prioritizing SIP network element, and the like, as wellas various combinations thereof). In one embodiment, dynamic propertiesconsidered for selecting between available output network connectionsmay include current network load, network congestion probabilities, andthe like, as well as various combinations thereof).

In one embodiment, PSPs configure network QOS parameters for IP packetswhich transport prioritized SIP messages using respective messagepriority levels of the SIP messages. In one embodiment, PSPs configureQOS parameters for IP packets which transport prioritized SIP messagesby setting values in IP packet headers (e.g., setting values to supportDiffServ). In one embodiment, PSPs configure QOS parameters for IPpackets which transport prioritized SIP messages by setting transportprotocol options (e.g., TCP selective acknowledgment, using differentStream Control Transmission Protocol (SCTP) streams, and the like, aswell as various combinations thereof).

In one embodiment, IP networks and routers may transport IP packetsconveying prioritized SIP messages according to respective messagepriority levels of the SIP messages. In one embodiment, in which PSPsconfigure network QOS parameters for IP packets which transportprioritized SIP messages using respective message priority levels of theSIP messages, downstream IP networks and associated routers may routethe IP packets according to the configured network QOS parameters. Inone embodiment, routers may process IP packets which transportprioritized SIP messages by mapping message priority levels into networktechnology specific configurations. In one such embodiment, for example,routers may map message priority levels of associated SIP messages toQOS classes of various standards such as IEEE 802.11(e), IEEE 802.1p,and the like.

In one embodiment, PSAPs configured to perform application specificoperations based on SIP message content may process prioritized SIPmessages based on respective message priority levels (e.g., based on theport on which each SIP message is received). In one embodiment, PSAPsmay be configured to perform application specific operations based onSIP message content. In one embodiment, in which a PSAP is configured toperform one application specific operation, SIP messages having aspecific message priority levels (or levels) may be routed to the PSAP.In one embodiment, in which a PSAP is configured to perform a pluralityof application specific operations, PSAP processing resources may bededicated to different application specific operations according tomessage priority levels of SIP messages processed by respectiveapplication specific operations.

As depicted in FIG. 1, PSP 130 ₁ assigns a message priority level toeach received SIP message. The PSP 130 ₁ processes the prioritized SIPmessages for determining routing of the prioritized SIP messages. TheSIP messages having priority levels one and two are assigned to port 132₁₋₁₂ for transmission to IP network 110 _(2A). The SIP messages havingpriority levels three and four are assigned to port 132 ₁₋₃₄ fortransmission to IP network 110 _(3A). The propagation of prioritized SIPmessages between PSP 130 ₁ and router 120 ₄ (i.e., over the portion ofthe end-to-end path between SIP UAC 102 _(C) and SIP UAS 102 _(s)supporting prioritized handling of SIP messages) is described hereinwith respect to the communication path between PSP 130 ₁ and router 120₄ configured for SIP messages having associated message priority levelsone and two.

The PSP 130 ₁ determines the next SIP network element to which each SIPmessage is transmitted (illustratively, PSAS 140 ₁). The PSP 130 ₁configures network QOS parameters for IP packets which transport therespective prioritized SIP messages. For SIP messages transmitted to IPnetwork 110 _(2A), PSP130 ₁ assigns QOS parameters which correspond tomessage priority levels one and two (denoted as QOS levels one (QOS₁)and two (QOS₂). The PSP 130 ₁ transmits prioritized SIP messages to PSAS140 ₁ via IP network 110 _(2A) using the assigned network QOSparameters. The prioritized SIP messages having message priority levelsone and two are received by PSAS 140 ₁ via ports 142 ₁₋₁ and 142 ₁₋₂,respectively. The PSAS 140 ₁ processes received IP packets to extractprioritized SIP messages.

The PSAS 140 ₁ determines the previously assigned message prioritylevels of prioritized SIP messages. In one embodiment, for example, PSAS140 ₁ determines the message priority level of each prioritized SIPmessage according to the port (e.g., ports 142 ₁₋₁ and 142 ₁₋₂) on whichprioritized SIP messages are received. The PSAS 140 ₁ (depending on theSIP message prioritization policy utilized by PSAS 140 ₁) may retain thepreviously assigned message priority level or determine and assign a newmessage priority level. The PSAS 140 ₁ processes prioritized SIPmessages according to respective message priority levels. Since P₁>P₂,processing of prioritized SIP messages by PSAS 140 ₁ is performed suchthat priority is given to SIP messages having message priority level one(P₁). The PSAS 140 ₁ transmits prioritized SIP messages to router 120 ₂via IP network 110 _(2A) using the assigned network QOS parameters. Therouter 120 ₂ routes prioritized SIP messages to PSP 130 ₂ via IP network110 _(2B) using the assigned network QOS parameters.

The PSP 130 ₂ determines the previously assigned message priority levelsof prioritized SIP messages. The PSP 130 ₂ (depending on the SIP messageprioritization policy utilized by PSP 130 ₂) may retain the previouslyassigned message priority level or determine and assign a new messagepriority level. In one embodiment, for example, PSP 130 ₂ determines themessage priority level of each prioritized SIP message according to theport (e.g., ports 132 ₂₋₁ and 132 ₂₋₂) on which prioritized SIP messagesare received. The PSP 130 ₂ processes prioritized SIP messages accordingto respective message priority levels. Since P₁>P₂, processing ofprioritized SIP messages by PSP 130 ₂ is performed such that priority isgiven to SIP messages having message priority level one. The PSP 130 ₂determines the next SIP network element to which each SIP message istransmitted (illustratively, router 120 ₄). The PSP 130 ₂ may leaveassigned QOS parameters unchanged or may modify the assigned network QOSparameters. The PSP 130 ₂ transmits prioritized SIP messages to router120 ₄ via IP network 110 _(2C) using the assigned/modified network QOSparameters.

The router 120 ₄ receives prioritized SIP messages having messagepriority levels of one or two from PSP 130 ₂ via IP network 110 _(2C).The router 120 ₄ receives prioritized SIP messages having messagepriority levels of three or four from PSP 130 ₃ via IP network 110_(3C). As depicted in FIG. 4, router 120 ₄ supports QOS levels QOS₁,QOS₂, QOS₃, and QOS₄ associated with SIP messages having messagepriority levels P₁, P₂, P₃, and P₄, respectively. The router 120 ₄routes prioritized SIP messages to SIP UAS 102 _(S) via external IPnetwork 104 _(S). In one embodiment, router 120 ₄ routes prioritized SIPmessages to SIP UAS 102 _(S) using the respective message prioritylevels. Upon processing received SIP messages, SIP UAS 102 _(S) maygenerate one or more SIP messages which may be transmitted to one ormore of the SIP network components of service provider domain 101, toSIP UAC 102 _(C) via service provider domain 101, and the like, as wellas various combinations thereof.

Since processing along the communication path between PSP 130 ₁ androuter 120 ₄ configured for SIP messages having associated messagepriority levels three and four is similar to processing along thecommunication path between PSP 130 ₁ and router 120 ₄ configured for SIPmessages having associated message priority levels one and two,processing along the communication path between PSP 130 ₁ and router 120₄ configured for SIP messages having associated message priority levelsthree and four is not described in detail herein. Since processing alongthe reverse communication between router 120 ₄ and PSP 130 ₁ isperformed in a manner similar to processing along the forwardcommunication path between PSP 130 ₁ and router 120 ₄ (irrespective ofmessage priority level), processing along the reverse communicationbetween router 120 ₄ and PSP 130 ₁ is not described herein.

As depicted in FIG. 1, each network component (on the portion of theend-to-end path between SIP UAC 102 _(C) and SIP UAS 102 _(S)) from PSP130 ₁ to router 110 ₄ is adapted for processing each SIP messageaccording to the associated message priority level. The message prioritylevel of a SIP message may be used for various functions (depending onthe network element processing the SIP message according to the messagepriority level), including selecting a next SIP network element,selecting a port within the next SIP network element, selecting anoutput network, selecting QOS parameters within the output network,processing the SIP message within the SIP network element according tothe message priority level, and the like, as well as variouscombinations thereof. The assignment of a message priority level to aSIP message and processing of SIP message within a SIP network elementaccording to the message priority level may be better understood withrespect to FIG. 3-FIG. 4 depicted and described herein.

Although primarily depicted and described herein as being performed by astandalone prioritization policy management system (illustratively,PPPMS 160), in one embodiment, prioritization policy managementfunctionality depicted and described herein may be performed by othernetwork elements. In one embodiment, prioritization policy managementfunctionality may be implemented as a portion of one of the prioritizingnetwork elements (illustratively, one of routers 120 ₂ or 120 ₃, PSPs130 or PSASs 140). In one embodiment, prioritization policy managementfunctionality may be implemented as a portion of one of the one of thenon-prioritizing network elements (illustratively, one of routers 120 ₂or 120 ₃, or network elements located within IP networks 110). In oneembodiment, prioritization policy management functionality may bedistributed across a plurality of network elements (illustratively,using various combinations of routers 120, PSPs 130, PSASs 140, and thelike, as well as various combinations thereof).

Although primarily depicted and described herein with respect to usingfour message priority levels (illustratively, message priority levelsP₁, P₂, P₃, and P₄), fewer or more message priority levels may beimplemented over at least a portion of a service provider domain forcontrolling SIP message prioritization processing on at least a portionof an end-to-end path between UAC and UAS. Although primarily depictedand described herein with respect to use of a constant number ofpriority levels along the portion of the end-to-end path between the UACand UAS for which message prioritization is supported (illustratively,between PSP 130 ₁ and router 120 ₄), in one embodiment, fewer or morepriority levels may be supported along various sub-portions of theend-to-end path between the UAC and UAS for which message prioritizationis supported.

As depicted in FIG. 1, router 120 ₂ supports priority levels one and twoand router 120 ₃ supports priority levels three and four, while router120 ₄ supports priority levels one, two, three, and four. In oneexample, although not depicted, router 120 ₂ may not be configured as aprioritizing network element (i.e., router 120 ₂ processes prioritizedSIP messages independent of respective message priority levels of theprioritized SIP messages). In another example, although not depicted,router 120 ₂ may be configured as a prioritizing SIP network elementsupporting additional message priority levels (e.g., router 120 ₂ mayfurther categorize the prioritized SIP messages such that prioritizedSIP messages having message priority level one may be assigned localizedmessage priority sub-levels (e.g., message priority levels P_(1A) andP_(1B)) such that processing within router 120 ₂ of SIP messages havingpriority level P₁ may vary according to the locally assigned messagepriority sub-levels.

Although primarily depicted and described herein with respect toestablishment of SIP message prioritization across a specific portion ofthe end-to-end path between UAC 102 _(C) and UAS 102 _(S), in oneembodiment, SIP message prioritization may be established over less ormore of the end-to-end path between UAC 102 _(C) and UAS 102 _(S). Inone embodiment, for example, SIP message prioritization may beestablished between less of the end-to-end path between UAC 102 _(C) andUAS 102 _(S). In one embodiment, for example, SIP message prioritizationmay be established between more of the end-to-end path between UAC 102_(C) and UAS 102 _(S) (illustratively, between router 120 ₁ and router120 ₄). In one embodiment, in which SIP UAC 102 _(C) is adapted forassigning message priority levels to respective SIP messages, SIPmessage prioritization may be established between the entire end-to-endpath between UAC 102 _(C) and UAS 102 _(S).

FIG. 2 depicts a method according to one embodiment of the presentinvention. Specifically, method 200 of FIG. 2 depicts a method forgenerating and distributing a prioritization policy. Although describedwith respect to determining and distributing one SIP messageprioritization policy, in one embodiment, different numbers of SIPmessage prioritization policies may be determined and distributed todifferent network elements. Although described with respect to specificinput information, other information described herein may be used fordetermining a SIP message prioritization policy. Although depicted asbeing performed serially, those skilled in the art will appreciate thatat least a portion of the steps of method 200 may be performedcontemporaneously, or in a different order than presented in FIG. 2. Themethod 200 begins at step 202 and proceeds to step 204.

At step 204, network configuration information is obtained. At step 206,network component capability information is obtained. At step 208,network component status information is obtained. At step 210, networkstatus information is obtained. At step 212, service information isobtained. In one embodiment, the network configuration information,network component capability information, network status information,and service information may be obtained from various combinations ofsystems (e.g., inventory systems, provisioning systems, maintenancesystems, and the like, as well as various combinations thereof), localdatabases, remote databases, network discovery, feedback messagesreceived from network components (e.g., from prioritizing SIP networkelements, from non-prioritizing SIP network elements, from non-SIPnetwork elements, and the like, as well as various combinationsthereof).

In one embodiment, network configuration information may include anyinformation specifying connectivity of network components. For example,network configuration information may include information that port 132₁₋₁₂ of PSP 132 ₁ is connected to IP network 110 _(2A) and port 132 ₁₋₃₄of PSP 132 ₁ is connected to IP network 110 _(3A). For example, networkconfiguration information may include information that router 120 ₂ isdisposed between IP networks 110 _(2A) and 110 _(2B). In one embodiment,network component capability information may include any informationspecifying functionality supported by various network components. Forexample, network component capability information may include SIPmessage load capacity of each of the PSPs 130, application-specificfunctions supported by each of the PSASs 140, quality of serviceparameters supported by each of the routers 120, and the like, as wellas various combinations thereof.

In one embodiment, network component status information includesinformation specifying status (e.g., actual, estimated, predicted, andthe like) of associated with the operation of various networkcomponents. For example, network component status information mayinclude resource usage status information such as CPU usage statusinformation, memory usage status information, and the like, as well asvarious combinations thereof associated with any network components(e.g., routers 120, PSPs 130, PSASs 140, and the like).

In one embodiment, network status information may include anyinformation specifying status (e.g., actual, estimated, predicted, andthe like) of various network components. For example, network statusinformation may include traffic load information (e.g., actual,estimate, and/or predicted traffic load information associated with oneor more network paths, network components, network addresses, messagetypes, dialog types, and the like, as well as various combinationsthereof), traffic routing information, network component failureinformation, link failure information, and the like, as well as variouscombinations thereof, associated with any network components (e.g., IPnetworks 110, routers 120, PSPs 130, PSASs 140, and the like).

In one embodiment, service information may include any informationassociated with services which may be supported by the network, as wellas services expected to be provided during specific times (e.g., day ofyear, day of week, time of day, and the like). For example, a largeamount of VoIP traffic may be expected on Easter, Christmas, and variousother holidays. For example, a large amount of VoIP traffic and instantmessage traffic to particular phone numbers or network addresses,respectively, may be expected due to a nationwide televisionentertainment show which requests that people vote for contestants bycalling specific telephone numbers or text messaging specific codes.

At step 214, a SIP message prioritization policy is determined. In oneembodiment, the SIP message prioritization policy is determined using atleast a portion of the network configuration information, networkcomponent capability information, network status information, serviceinformation, and the like, as well as various combinations thereof. Inone embodiment, the SIP message prioritization policy may be determinedusing various combinations of other information described herein. Atstep 216, the SIP message prioritization policy is distributed. The SIPmessage prioritization policy may be distributed using any policydistribution scheme. At step 218, method 200 ends.

Although described with respect to one SIP message prioritizationpolicy, in one embodiment, multiple SIP message prioritization policiesmay be determined (e.g., for a network, a portion of a network, anetwork component, and the like). In one such embodiment, for example,one or more of the SIP message prioritization policies may bedistributed to a network, a portion of a network, a network component,and the like, as well as various combinations thereof. In oneembodiment, for example, multiple SIP message prioritization policiesmay be determined for distribution to multiple prioritizing SIP networkelements on at least a portion of an end-to-end path between a SIPclient (e.g., SIP UAC) and a SIP server (e.g., SIP UAS).

In continuation of the example in which hereinabove, in which a largeamount of instant message and VoIP traffic may be expected to particularnumbers/addresses due to a nationwide television entertainment showwhich requests that people vote by text messaging or calling specifictelephone numbers, the service provider may determine a SIP messageprioritization policy adapted to support the additional SIP messagegenerated as a result of the television show while maintaining highquality of service for high-priority emergency traffic. For example,separate networks, network links, servers, and like network componentsmay be dedicated to support the additional SIP messages generated as aresult of the television show, while other networks, network links,servers, and like network components may be dedicated to support SIPmessages associated with an emergency call center. The prioritizationpolicy, once distributed to the network components, guarantees unchangedquality to regular customers and good quality to voting customers.

As described herein, prioritizing SIP network elements may use SIPmessage prioritization functions for performing SIP messagedifferentiation under various conditions. In one embodiment,prioritizing SIP network elements may use SIP message prioritizationfunctions for providing service differentiation. In one embodiment,prioritizing SIP network elements may use SIP message prioritizationfunctions for providing customer differentiation. In one embodiment,prioritizing SIP network elements may use SIP message prioritizationfunctions for providing SIP message filtering. In one embodiment,prioritizing SIP network elements may use SIP message prioritizationfunctions for providing SIP message policing. Although described withrespect to specific functionality capable of being implemented in a SIPnetwork element, various other functions may be supported by SIP networkelements utilizing SIP message prioritization functions.

In one embodiment, prioritizing SIP network elements may use SIP messageprioritization functions for providing service differentiation. A SIPnetwork element can receive a variety of different SIP message types(e.g., REGISTER, INVITE, MESSAGE, PUBLISH, SUBSCRIBE, NOTIFY). Intypical implementations, SIP INVITE messages are used for VoIP,multimedia sessions, push-to-talk (PTT), and the like, SIP MESSAGEmessages are used for instant messaging, and SIP PUBLISH, SUBSCRIBE,NOTIFY messages are used for presence. In one embodiment, SIP messagetypes may be used for prioritizing SIP messages. For example, in oneembodiment, real-time services (initiated by SIP INVITE messages) may beassigned higher priority than non-real-time services such as instantmessaging and presence. In one embodiment, in which different servicesuse the same SIP message type(s) (e.g., PTT services and non-emergencyVoIP services), service differentiation requires consideration ofadditional non-service-related parameters.

In one embodiment, prioritizing SIP network elements may utilize SIPmessage prioritization functions for providing customer differentiation.Since SIP message prioritization may utilize any information includedwithin SIP messages, in one embodiment, SIP message prioritization maybe performed using SIP message header fields adapted for differentiatingbetween different customers (e.g., “From:” field name and associatedfield value, “To:” field name and associated field value, and the like,as well as various combinations thereof). In one embodiment, in whichSIP network elements are adapted for providing customer differentiation,service providers may introduce various service offerings (e.g., bronze,silver, and gold). In one embodiment, in the context of IMS, the“P-Asserted-Identity” header field may be used in place of the “From:”header fields for providing customer differentiation.

In one embodiment, prioritizing SIP network elements may utilize SIPmessage prioritization functions for providing SIP message filtering andpolicing. For example, message prioritization policies may be definedsuch that different enterprise customers are served according to servicelevel agreements, and excessive SIP messages from one customer can befiltered and rejected in order to avoid violation of service levelagreements associated with other customers. In one such embodiment, theservice level agreements may be specific to IMS services, and mayinclude parameters not typically negotiated with respect to servicelevel agreements (e.g., average and maximum numbers of sessions,presence messages, instant messages, and the like, as well as variouscombinations thereof). In one embodiment, given appropriateclassification criteria based on SIP spam detection algorithms, messagefiltering capabilities may be applied to remove unsolicited SIP spammessages.

As described herein with respect to FIG. 1 and FIG. 2, centralizedprioritization policy management enables a coordinated treatment ofmessage priority levels across SIP network elements. The coordinatedtreatment of message priority levels across SIP network elementsrequires initial prioritization of each SIP message by a prioritizingSIP network element, as well as support for processing of eachprioritized SIP message by each prioritizing SIP network element. Theinitial prioritization of SIP messages by a prioritizing SIP networkelement (and subsequent processing of prioritized SIP messages withinthe prioritizing SIP network element) according to respective assignedmessage priority levels may be better understood with respect to FIG. 3and FIG. 4 depicted and described herein.

As described herein, despite careful network engineering, situations mayarise in which a SIP network element within a service provider domaintemporarily receives more messages than the SIP network element iscapable of processing, often resulting in delaying of SIP messages and,sometimes, dropping of SIP messages. The delaying and dropping of SIPmessages may result in various network quality problems, such asdecreases in user-perceived quality (e.g., unacceptable call setuptimes), failure of critical services (e.g., failure of emergency calls),and the like. In one embodiment, a prioritizing SIP network element maydifferentiate between SIP messages using a message prioritizationmechanism which controls priority-based processing of SIP messageswithin the prioritizing SIP network element. The use of SIP messageprioritization within a SIP network element enables end-to-end SIPmessage prioritization within SIP-based networks.

The number of messages in a SIP network element represents the load ofthe SIP network element. A high-load condition associated with a SIPnetwork element may be defined as a condition in which the SIP networkelement receives more messages than it is capable of processing within acertain time interval. In one embodiment, under a high-load condition,the SIP network element retains control over the processing of theexcess SIP messages. An overload condition associated with a SIP networkelement may be defined as a condition in which a message threshold(e.g., the number of SIP messages for which the SIP network element isdesigned or dimensioned) is exceeded such that a portion of the SIPmessages may become beyond the control of the SIP network element. Theuse of SIP message prioritization within a SIP network element enablesmore efficient handling of SIP messages under high-load, overload, andlike conditions.

FIG. 3 depicts a high-level block diagram of a prioritizing SIP networkelement. Although primarily depicted and described as a standalone SIPnetwork element adapted for prioritizing SIP messages using one or moreSIP message prioritization policies and processing prioritized SIPmessage using respective assigned message priority levels, it should benoted that prioritizing SIP network element 300 may operated within thecontext of a network including other prioritizing SIP network elementsas depicted and described herein with respect to FIG. 2 and FIG. 3.Thus, although primarily described herein from the perspective of astandalone SIP network element, it should be noted that prioritizing SIPnetwork element 300 may be used for conveying message priority levels ofassociated SIP messages between other prioritizing SIP network elements(not depicted).

As depicted in FIG. 3, prioritizing SIP network element 300 includes aninput port (IP) 301 _(I), an input network socket buffer (INSB) 302_(I), a prioritization stage (PS) 310, a message priority queue (MPQ)320, a processing stage (PS) 330, an output network socket buffer (ONSB)302 _(O), and an output port (OP) 301 _(O). The IP 301 _(I), INSB 302_(I), PS 310, MPQ 320, PS 330, ONSB 302 _(O), and OP 301 _(O) arecontrolled by a controller 340. The PS 310 includes a plurality ofprioritization threads (PTs) 312 ₁-312 _(N) (collectively, PTs 312). ThePS 330 includes a plurality of processing threads (PTs) 332 ₁-332 _(N)(collectively, PTs 332). Although depicted and described with respect toone input port and one output port, prioritizing SIP network elementsmay include additional input ports and output ports.

As depicted in FIG. 3, incoming messages are received at IP 301 _(I).Since SIP allows use of several transport protocols, includingconnection-oriented protocols (e.g., TCP, SCTP, and the like) andconnectionless protocols (e.g., UDP), various different message typesmay be received at IP 301 _(I). The reception of messages is handled bywaiting for the incoming messages. The incoming messages received at IP301 _(I) are read into INSB 302 _(I). The incoming messages stored inINSB 302 _(I) are processed in order to convert the incoming messagesinto SIP messages. The amount of processing required to convert theincoming messages into SIP messages depends on the transport protocol.For example, for UDP the complete SIP message is included within asingle UDP packet, whereas TCP is a stream-based protocol withoutbuilt-in message boundaries. For TCP, a SIP message boundary is found byscanning the incoming byte stream to find the content-length headervalue and the end-of-header marker. If transport layer security (TLS) isemployed, decryption processing is performed.

As depicted in FIG. 3, SIP messages from INSB 302 _(I) are processed byPS 310. The PS 310 process SIP messages in order to convert each SIPmessage from the wire format (i.e., SIP) to an internal message datastructure including the SIP message header (i.e., SIP message headerfields including respective SIP message header field names andassociated SIP message header field values) and the SIP message content.The PS 310 parses each SIP message in order to determine a messagepriority level associated with the SIP message. The determined messagepriority levels are assigned to the respective SIP messages for use inprocessing the SIP messages. The PS 310 performs parsing andprioritization of SIP messages using a plurality of parsing andprocessing threads (illustratively, PTs 312).

In order to determine the message priority level of a SIP message, atleast a portion of the message must be parsed. Since such parsing isrequired regardless of the message priority level (since the messagepriority level is not yet assigned), parsing should be performed asefficiently as possible so as not to waste message parsing resources onlow priority messages which may be rejected later. The SIP message isparsed in order to determine information adapted for use in determiningan associated message priority level. A SIP message prioritizationpolicy is applied to the information in order to determine and assign anassociated message priority level to each SIP message. In oneembodiment, in which multiple SIP message prioritization policies areavailable, at least a portion of the information may be used to selectthe SIP message prioritization policy used to determine and assign theassociated message priority level.

In one embodiment, in order to determine a message priority level of aSIP message, at least a portion of the associated SIP message header maybe parsed. In one embodiment, the message priority level may bedetermined using one or more SIP message header fields (e.g., parsingrespective SIP message header field names and associated SIP messageheader field values). In one embodiment, for example, the messagepriority level of a SIP message may be determined using at least oneassociated SIP message characteristic (e.g., SIP message type, SIPmessage length, and the like, as well as various combinations thereof).The SIP message type may be determined by parsing at least a portion ofthe SIP message header (e.g., the first line of the SIP message header).Although primarily described with respect to parsing of SIP messageheaders in order to determine message priority levels, other informationmay be used to determine message priority levels.

In one embodiment, SIP messages may include respective header fieldsindicative of message importance which may be used to determine anassociated message priority level. In one embodiment, for example, a SIPmessage header may include a “Priority:” header field name. In thisexample, the “Priority:” header field name indicates the importance ofthe request to the receiver, and the associated SIP message header fieldvalue may include one of non-urgent, normal, urgent, or emergency. Inone embodiment, for example, a SIP message header may include a“Resource-Priority:” header field name. In this example, the“Resource-Priority:” header field name indicates the importance of thededicating resources to the SIP message, and may include severalpriority levels for distinct domains (e.g., namespaces). As describedherein, in one embodiment, such header fields indicating respectivemessage importance may be mapped into a corresponding message prioritylevel; however, since not all SIP messages include such information,determination and assignment of message priority levels may be performedusing various other parameters, fields, values, and the like, as well asvarious combinations thereof.

As depicted and described herein with respect to network-level SIPmessage prioritization, in one embodiment, prioritization of SIPmessages may be performed using one or more SIP message prioritizationpolicies distributed to the SIP network element by a centralprioritization policy management system (illustratively, PPMS 160). Inone such embodiment, SIP message prioritization policies may use variouscombinations of SIP message prioritization factors for prioritizing SIPmessages. In one embodiment, in which a SIP message prioritizationpolicy does not account for certain SIP message prioritization factors,prioritizing SIP network elements may perform SIP message prioritizationusing one or more SIP message prioritization policies in conjunctionwith one or more SIP message prioritization factors.

In one embodiment, SIP message prioritization factors may include one ormore of network characteristics (e.g., network traffic patterns, networktraffic load, and the like, as well as various combinations thereof),prioritizing SIP network element type (e.g., prioritization of SIPmessages may differ for UACs, PSPs, PSASs, UASs, and the like),prioritizing SIP network element load characteristics, SIP messagecharacteristics (e.g., SIP message type, SIP message length, and thelike, as well as various combinations thereof), SIP message headerfields (including respective SIP message header field names andassociated SIP message header field values), SIP message content fields(including SIP message content field names and associated SIP messagecontent field values), time (e.g., day of year, day of week, time ofday, and the like), service provider requirements, and the like, as wellas various combinations thereof.

The assignment of the determined message priority level to the SIPmessage may be performed using at least one of a plurality messagepriority level assignment schemes. In one embodiment, selection of theat least one message priority level assignment scheme may bepre-configured. In one embodiment, selection of the at least one messagepriority level assignment scheme may be performed using the SIP messageprioritization policy. In one embodiment, the determined messagepriority level of a SIP message may be determined and, optionally,maintained, by a controller (illustratively, controller 340).

In one embodiment, a determined message priority level may be assignedto a SIP message by providing an indication of the message prioritylevel within the SIP message. In one embodiment, the message prioritylevel may be assigned by modifying at least a portion of the SIP messageheader (e.g., adding a SIP message header field having a SIP messageheader field name and value, modifying a SIP message header field valueof an existing SIP message header field, and the like, as well asvarious combinations thereof). In one embodiment, message priority levelmay be assigned by adding an additional SIP message header. In oneembodiment, the message priority level may be assigned by modifying atleast a portion of the SIP message body (e.g., adding a SIP message bodyfield having a field name and value, modifying a SIP message body fieldvalue of an existing SIP message body field, and the like, as well asvarious combinations thereof).

In one embodiment, a determined message priority level may be assignedto a SIP message by associating the SIP message with one of a pluralityof message processing threads (illustratively, PTs 332) according to themessage priority level. In one embodiment, for example, in which a SIPmessage prioritization policy defines four message priority levels, fourmessage processing threads may be maintained by a controller such thateach message processing thread is associated with a different one of thefour message priority levels (i.e., a SIP message determined to have aparticular message priority level is assigned to the message processingthread associated with that message priority level).

Although described with respect to a one-to-one relationship betweenmessage priority level and message processing thread, in various otherembodiments, SIP messages determined to have one or more of the messagepriority levels may be assigned to one of a plurality of messageprocessing threads (e.g., more message processing threads are availablefor processing higher priority messages), multiple message prioritylevels may be assigned to one message processing thread (e.g., SIPmessages with message priority levels of one and two are assigned to afirst message processing thread while SIP messages with message prioritylevels of three and four are assigned to a second message processingthread), and the like, as well as various combinations thereof.

In one embodiment, a determined message priority level may be assignedto a SIP message by positioning of the SIP message within a messagepriority queue. The SIP message is positioned within the messagepriority queue according to the determined message priority level of theSIP message and the respective message priority levels of SIP messagesin the message priority queue at the time that the SIP message isassigned to the message priority queue. In one embodiment, positioningof a SIP message within a message priority queue may include locating aninsertion position within the message priority queue according to theassigned message priority level of the SIP message being queued and aplurality of other assigned message priority levels of a respectiveplurality of other SIP messages queued within the message priorityqueue, and inserting the SIP message within the located insertionposition.

As depicted in FIG. 3, prioritized SIP messages are queued in MPQ 320.In one embodiment, prioritized SIP messages are queued within MPQ 320according to the respective message priority levels such that averagequeuing delay of higher priority SIP messages is less than averagequeuing delay of lower priority SIP messages. Since incoming SIPmessages may be assigned higher message priority levels than messagepriority levels of SIP messages current queued in MPQ 320,prioritization of arriving SIP messages may cause reordering of SIPmessages within MPQ 320. The re-ordering of prioritized SIP messageswithin MPQ 320 does not violate the protocol rules of the SIP protocol.

Although primarily depicted and described with respect to a prioritizingSIP network element including one message priority queue, in variousother embodiments, multiple message priority queues may be used forassigning message priority levels to SIP messages. In one embodiment,for example, in which a SIP message prioritization policy defines fourmessage priority levels, four message priority queues may be utilizedsuch that each message priority queue is associated with a different oneof the four message priority levels (i.e., a SIP message determined tohave a particular message priority level is assigned to the messagepriority queue associated with that message priority level).

Although described with respect to a one-to-one relationship betweenmessage priority level and message priority queue, in various otherembodiments, SIP messages determined to have one or more of the messagepriority levels may be assigned to one of a plurality of messagepriority queues (e.g., more message priority queues are available forprocessing higher priority messages), multiple message priority levelsmay be assigned to one message priority queue (e.g., SIP messages withmessage priority levels of one and two are assigned to a first messagepriority queue while SIP messages with message priority levels of threeand four are assigned to a second message priority queue), and the like,as well as various combinations thereof.

In one embodiment, SIP network element 300 may control which SIPmessages are prioritized (or discarded/rejected) during load conditions(e.g., high-load conditions, overload conditions, and the like). In oneembodiment, upon detection of one or more load conditions, one or moreSIP messages may be discarded. In one embodiment, upon detection of oneor more load conditions, one or more SIP messages may be rejected. Inone embodiment, selection between discarding and rejection of each SIPmessage may be performed using at least one of the SIP messageprioritization policy, one or more load condition characteristics (e.g.,extent of the load condition such high-load conditions versus overloadconditions, the duration of the load condition, and the like, as well asvarious combinations thereof), respective message priority levels of theSIP messages, and the like, as well as various combinations thereof.

In one embodiment, selection of which SIP messages to discard/reject maybe performed using at least one of a plurality of message discard/rejectfactors. In one embodiment, selection of which SIP messages todiscard/reject may be performed using respective message priority levelsof SIP messages available for selection to be discarded/rejected (e.g.,SIP messages assigned the lowest message priority level arediscarded/rejected first, and so on). In one embodiment, selection ofwhich SIP messages to discard/reject may be performed using the SIPmessage prioritization policy. In one embodiment, selection of which SIPmessages to discard/reject may be performed using one or more SIPmessage characteristics (e.g., message type, dialog type, and the like,as well as various combinations thereof). In one embodiment, selectionof which SIP messages to discard/reject may be performed using one ormore load condition characteristics.

In one embodiment, selection of which SIP messages to discard/reject maybe performed using status information. In one embodiment, selection ofwhich SIP messages to discard/reject may be performed using networkelement status information such as current network element statusinformation (e.g., CPU load, memory usage, and like parametersassociated with the current network element on which prioritization ofSIP messages is performed). In one embodiment, selection of which SIPmessages to discard/reject may be performed using network statusinformation such as network resource information (e.g.,discarding/rejecting SIP messages intended for a network having minimalnetwork resources), network traffic load information (e.g.,discarding/rejecting SIP messages intended for a network with a hightraffic load), and the like, as well as various combinations thereof.

As described herein, in one embodiment, selection of which SIP messagesto discard/reject may be performed using a plurality of messagediscard/reject factors. In one such embodiment, for example, in whichSIP messages assigned the lowest priority level outnumber the number ofSIP messages which must be discarded/rejected in response to a loadcondition, selection among the SIP messages assigned the lowest messagepriority level may be performed according to the SIP messageprioritization policy such that SIP messages having specific messagetypes or belonging to specific dialog types are selected to bediscarded/rejected prior to SIP messages having other specific messagetypes or belonging to other specific dialog types.

Although primarily described herein with respect to either discardingSIP messages or rejecting SIP messages, in one embodiment, aprioritizing SIP network element may perform combinations of discardingand rejecting of SIP messages. In one embodiment, for example, inresponse to detection of a load condition, SIP messages assigned thelowest message priority level may be classified according to respectivemessage types of the SIP messages assigned the lowest message prioritylevel such that SIP messages having one specific message type arediscarded while SIP messages having another specific message type arerejected. Although described with respect to specific parameters, invarious other embodiments, various other parameters may be used by aprioritizing SIP network element for selecting between discarding andrejecting SIP messages.

In one embodiment, MPQ 320 enables SIP network element 300 to controlwhich SIP messages are prioritized (or discarded/rejected) during loadconditions. In the absence of MPQ 320, SIP messages may be arbitrarilydropped from network buffers (illustratively, NSB 302 _(I)) in responseto various conditions (e.g., if respective capacities of the networkbuffers cross a threshold, if respective capacities of network buffersare exceeded, and the like). In order to ensure that SIP messages areprioritized prior to being discarded/rejected under load conditions: 1)sufficient SIP network element resources must be allocated to readingincoming SIP messages from network buffers into MPQ 320 and 2) effectiveSIP message prioritization (or discard/rejection) processing must beperformed on messages received from network buffers prior to queuing ofthe prioritized SIP messages in MPQ 320.

Since SIP messages are typically retransmitted if not processed within acertain time interval, the maximum number of SIP messages queued in MPQ320 has a practical limit, and increasing the length of MPQ 320 isgenerally ineffective to handle load conditions. In one embodiment, SIPnetwork element 30 may discard (i.e., drop) SIP messages in response toa load condition. In another embodiment, since simply discarding SIPmessages may trigger one or more SIP message retransmissions which mayexacerbate load conditions, rather than discarding messages under loadconditions, SIP network element 300 may include SIP message rejectionprocessing. In one such embodiment, since message retransmission is animportant aspect of the SIP protocol, message retransmission may beaccounted for in the SIP message rejection strategy employed withinprioritizing SIP network elements.

The effects of message dropping may be illustrated with the followingexample. For example, after sending a request message, a correspondingresponse message (e.g., a 2xx response, indicating a successful request)is expected. As an exception, the sender of a 2xx response message on anINVITE message expects an ACK request message in reply. If a responsemessage is not received within a certain time interval, the requestmessage is typically retransmitted. For example, for UDP, an INVITEmessage is retransmitted according to an exponential back-off scheme inwhich the interval is doubled each period (e.g., it defaults to 0.5, 1,2, 4, 8, and 16 seconds, i.e., up to 6 retransmissions). As anotherexample, for any transport protocol, a 2xx response to an INVITE messageis by default retransmitted up to ten times according to the scheme:0.5, 1, 2, 4, . . . , 4 seconds).

The effects of message dropping may be further illustrated with thefollowing examples. The dropping of a request sent over an unreliabletransport (UDP) will eventually trigger a retransmission by the sender(unless it was the last retransmission). The dropping of a non-INVITEresponse sent over UDP will eventually trigger a retransmission by thecorresponding request by the original sender, which will cause aretransmission of the response (if the retransmitted request arrives).The dropping of a 2xx response to an INVITE will eventually trigger aretransmission of the response on any transport. This retransmissionends when an ACK is received. As described herein, in some instances, inorder to prevent detrimental effects of retransmissions triggered inresponse to discarding of SIP messages, a SIP message rejection strategyimplemented as a portion of the prioritizing SIP network element.

In one embodiment, under load conditions, rather than discarding SIPmessages, SIP messages may be rejected. In one embodiment, rejection ofSIP messages according to message priority levels may be performed in amanner for preventing retransmissions. In one embodiment, in order toavoid retransmissions, rather than rejecting SIP messages, the SIPnetwork element may respond with an error message (e.g., 503 serviceunavailable for congestion control). In one such embodiment, a“Retry-After:” may be inserted within the SIP message header to extendthe amount of time that passed before retransmission of the SIP messageis attempted (attempting to ensure that the next time that SIP messageis received the SIP network element is no longer experiencing ahigh-load condition, overload condition, or any other like conditions).In one embodiment, error messages may be prioritized (e.g., assigned amessage priority level) using a SIP message prioritization policy andprocessed using the SIP message priority level.

As depicted in FIG. 3, prioritized SIP messages from MPQ 320 areprocessed by PS 330. The PS 330 processes prioritized SIP messages,according to the respective assigned message priority levels, using aplurality of processing threads in parallel (illustratively, PTs 332).The processing of prioritized SIP messages depends on system state.During processing of prioritized SIP messages, system state is updatedaccording to SIP protocol rules which may include proprietary rules,rules defined in various Internet standards, RFCs, and the like (e.g.,RFC3261, RFC3263, and the like), and the like, as well as variouscombinations thereof. The processing of prioritized SIP messages dependson various processing factors such as prioritization policy,prioritizing SIP network element type, prioritized SIP message type, andthe like, as well as various combinations thereof.

The processing of prioritized SIP messages may depend on the processingfunctions supported by the prioritizing SIP network element (e.g.,depending on the prioritizing SIP network element type). For example,processing of SIP messages may differ for UACs, PSPs, PSASs, UASs, andthe like. The processing of prioritized SIP messages may depend on oneor more SIP message prioritization policies, other processing policies,and the like, as well as various combinations thereof. Under certaincircumstances, processing of prioritized SIP messages may requireinteraction with external systems (e.g., performing DNS lookups,retrieving information from various databases, and the like, as well asvarious combinations thereof).

In one embodiment, priority-based message processing performed by PS 330may be implemented as a strict priority-based message processing scheme.In a strict priority-based message processing scheme, message prioritylevels assigned to respective SIP messages determines relative order inwhich SIP messages are processed by PS 330 (i.e., influences how messageprocessing wait time is distributed over SIP messages having differentassociated message priority levels, thereby resulting in lower averagedelay times for higher priority SIP messages at the cost of higheraverage delay times for lower priority SIP messages). Since a strictpriority-based message processing scheme may have a risk of messagestarvation (which occurs when there are so many high priority messagesthat low priority messages do not get processed), various otherpriority-based message processing schemes may be used in accordance withthe present invention.

In one embodiment, priority-based message processing performed by PS 330is implemented as a weighted priority-based message processing scheme.In a weighted priority-based message processing scheme, weights may beassigned to the various message priority levels. The assigned weightsmay be static or dynamic weight assignments. In one embodiment,priority-based message processing performed by PS 330 is implemented asa strict-weighted priority-based message processing scheme. In astrict-weighted priority-based message processing scheme, absolutepriority may be given to a portion of the message priority levels andweights may be assigned to the remaining message priority levels. In onesuch embodiment, for example, absolute priority may be given to thehighest message priority level(s) and proportional weights may beassigned to the lower priority level(s).

In one embodiment, PTs 332 of PS 330 process SIP messages in order toconvert each SIP message from an internal data structure formatincluding the SIP message header (including SIP message header fieldnames and associated SIP message header field values) and the SIPmessage content to the wire format (i.e., SIP). The SIP messages may beprioritized SIP messages (e.g., in a network configured for providingcross-element prioritization of SIP messages) or non-prioritized SIPmessages (e.g., in a network in which SIP message prioritization isconfined to use within SIP network elements). The message bytes of theSIP messages are serialized and buffered in ONSB 302 _(O). The bufferedSIP message bytes are transmitted using OP 301 _(O).

As depicted in FIG. 3, prioritizing SIP network element 300 is adaptedto propagate determined/assigned message priority levels of SIP messagesto other network elements. As described herein, prioritizing SIP networkelement 300 may propagate message priority levels of SIP messages usingone or more message priority level propagation methods. In oneembodiment, a message priority level may be propagated by modifying theSIP message (e.g., modifying one or more SIP message header fieldvalues, adding one or more SIP message header fields includingassociated SIP message header field names and corresponding SIP messageheader field values, modifying one or more SIP message body fieldvalues, and the like, as well as various combinations thereof). In onesuch embodiment, modification of the SIP message to support propagationof the message priority level is performed during assignment of thedetermined message priority level.

In one embodiment, a message priority level may be propagated byassigning the SIP message to traverse a particular network(illustratively, assigning a SIP message to traverse IP network 110_(2A) rather than IP network 110 _(3A)), assigning the SIP message to bedelivered to a network element (illustratively, assigning a SIP messageto be delivered to PSAS 140 ₁ rather than PSAS 140 ₂), and the like, aswell as various combinations thereof. In one embodiment, a messagepriority level may be propagated by assigning the SIP message to aparticular output port on the source network element from which the SIPmessage is transmitted. In one embodiment, a message priority level maybe propagated by assigning the SIP message to a particular input port onthe destination network element to which the SIP message is transmitted.

Although primarily described herein with respect to initialprioritization of SIP messages, in one embodiment, since at least aportion of the received SIP messages may include prioritized SIPmessages (i.e., previously prioritized by upstream prioritizing SIPnetwork elements), prioritizing SIP network element 300 may performprocessing in order to identify previously assigned message prioritylevels of received SIP messages. In one embodiment, prioritizing SIPnetwork element 300 may determine whether each received SIP messagealready has an assigned message priority level. In one embodiment, PS310 may parse at least a portion of each received SIP message (e.g.,parsing a portion of a SIP message header) to determine whether amessage priority level was previously assigned, determine a previouslyassigned message priority level, and the like. In one embodiment, theSIP message prioritization policy implemented by prioritizing SIPnetwork element 300 may use the previously assigned message prioritylevel in order to determine and assign the message priority level.

Although primarily depicted and described with respect to use of oneprioritization stage, one message priority queue, and one processingstage for handling SIP messages for one IP input port and one IP outputport, prioritizing SIP network elements may include additional inputports and output ports. In one embodiment, a prioritization stage, amessage priority queue, and a processing stage may be dedicated tohandling SIP messages for one input port and one output port. In oneembodiment, various combinations of one or more prioritization stages,one or more message priority queues, and one or more processing stagesmay be dedicated to handling SIP messages for one input port and oneoutput port. In one embodiment, various combinations of one or moreprioritization stages, one or more message priority queues, and one ormore processing stages may be dedicated to handling SIP messages formultiple input ports and multiple output ports.

Although primarily depicted and described herein with respect to use ofparallel threads (illustratively, parallel PTs 312 and parallel PTs332), various other threading strategies may be utilized forparsing/prioritizing or processing SIP messages. In one embodiment, forexample, controller 340 (or another module) may maintain a thread poolof available threads. In one such embodiment, controller 340 may selecta parsing/prioritizing thread from the thread pool for each SIP messageentering PS 310 and select a processing thread from the thread pool foreach SIP message entering PS 330. Although depicted and described hereinwith respect to use of various threading strategies, various otherthreading strategies may be used in accordance with the presentinvention.

FIG. 4 depicts a method according to one embodiment of the presentinvention. Specifically, method 400 of FIG. 4 depicts a method forprocessing a received SIP message at a prioritizing network element.Although depicted as being performed serially, those skilled in the artwill appreciate that at least a portion of the steps of method 400 maybe performed contemporaneously, or in a different order than presentedin FIG. 4. The steps of method 400 may be better understood with respectto prioritizing SIP network element 300 depicted and described hereinwith respect to FIG. 3. The method 400 begins at step 402 and proceedsto step 404.

At step 404, a SIP message is received. The SIP message may be receivedfrom any network element (SIP or non-SIP, prioritizing ornon-prioritizing, and the like). At step 406, the SIP message header ofthe received SIP message is parsed. In one embodiment, the parsing isperformed in a manner for minimizing at least one of a size of theparsed portion of a SIP message header, a parsing time during which theSIP message header is parsed, and the like, as well as variouscombinations thereof. The parsing of the received SIP message may beperformed using various parsing algorithms. In one embodiment, forexample, parsing of the SIP message may be performed using at least aportion of the SIP message parsing functions described in the patentapplication entitled “Method and Apparatus For Identifying Message FiledNames” (patent application Ser. No. 11/318,843).

At step 408, the message priority level of the received SIP message isdetermined using at least one SIP message prioritization policy. In oneembodiment, the message priority level of the received SIP message isdetermined using the SIP message prioritization policy in conjunctionwith information obtained from the parsing of the SIP message header. Inone embodiment, the message priority level of the received SIP messagemay be determined using a plurality of SIP message prioritizationpolicies, various portions of a plurality of SIP message prioritizationpolicies, and the like, as well as various combinations thereof.

In one embodiment, determining the message priority level of the SIPmessage may include determining whether the received SIP message waspreviously prioritized (i.e., whether the received SIP message has anassigned message priority level assigned by an upstream SIP networkelement). In one embodiment, in which the assigned message prioritylevel is conveyed in the SIP message header, the determination as towhether the received SIP message is a prioritized SIP message may bemade using information from parsing of the SIP message header. In oneembodiment, in which the SIP message prioritization policy accounts forpreviously assigned message priority level, the current message prioritylevel of the received SIP message may be determined, at least in part,using the previously assigned message priority level.

At step 410, the determined message priority level is assigned to theSIP message. In one embodiment, the assignment of the message prioritylevel to the SIP message may be performed using one of a pluralitymessage priority level assignment schemes described herein (e.g.,positioning the SIP message within a queue, assigning the SIP message toone of a plurality of queues, assigning the SIP message to one of aplurality of message processing threads, modifying the message header,and the like, as well as various combinations thereof). At step 412, theprioritized SIP message is queued. In one embodiment, the prioritizedSIP message is queued according to the determined and assigned messagepriority level. At step 414, a determination is made as to whether toprocess the SIP message.

In one embodiment, the determination as to whether to process the SIPmessage depends on whether a load condition is detected by theprioritizing SIP network element during the time during which theprioritized SIP message is queued. In one embodiment, in no loadcondition is detected during the time during which the prioritized SIPmessage is queued, the prioritized SIP message is processed. In oneembodiment, in a load condition is detected during the time during whichthe prioritized SIP message is queued, the prioritized SIP message mayor may not be processed depending on various factors described herein(e.g., extent of the load condition, assigned message priority leve, SIPmessage prioritization policy, and the like, as well as variouscombinations thereof).

In one embodiment, the prioritizing SIP network element monitors fordetection of load conditions. In one embodiment, the determination as towhether a load condition is detected may be performed by monitoringvarious load status parameters of the prioritizing SIP network element(e.g., CPU load, memory usage, queue capacity, and the like, as well asvarious combinations thereof). In one embodiment, for example, ahigh-load condition may be detected when one or more of the load statusparameters reaches 75% utilization (e.g., message priority queue is 75%utilized) and an overload condition may be detected when one or more ofthe status parameters reaches 90% utilization (e.g., message priorityqueue is 75% utilized). In one embodiment, the determination as towhether a load condition is detected may be performed using variousother factors.

If the SIP message is not processed, method 400 proceeds to step 416. Atstep 416, a determination is made as to whether to discard the SIPmessage or reject the SIP message. As described herein, the decision asto whether a SIP message is discarded or rejected may be based onvarious combinations of parameters and information. If the SIP messageis to be discarded, method 400 proceeds to step 418 where the SIPmessage is discarded, as described herein. If the SIP message is to berejected, method 400 proceeds to step 420 where the SIP message isrejected, as described herein. From steps 418 and 420, method 400proceeds to step 426, where method 400 ends. If the SIP message isprocessed, method 400 proceeds to step 422.

At step 422, the SIP message is parsed. In one embodiment, the SIPmessage header is parsed. In one such embodiment, only the portion ofthe SIP message header not previously parsed to determine the messagepriority level is parsed. In one embodiment, at least a portion of theSIP message content is parsed. At step 424, the SIP message is processedfor performing at least one function (e.g., routing the SIP message,performing an application-specific function, and the like, as well asvarious combinations thereof). As described herein, the prioritized SIPmessage may be processed using the information obtained during theparsing of the prioritized SIP message. From step 424, method 400proceeds to step 426 where method 400 ends.

FIG. 5 depicts a high-level block diagram of a prioritizationarchitecture from the perspective of a plurality of prioritizing SIPnetwork elements using associated SIP message prioritization policiesfor prioritizing SIP messages and processing SIP messages using messagepriority levels of the prioritized SIP messages. Specifically,prioritization architecture 500 of FIG. 5 includes pluralities ofnetwork elements 502 ₁-502 _(N) (collectively, network elements 502), aplurality of prioritizing SIP network elements 510 ₁-510 _(N)(collectively, prioritizing SIP network elements 510), pluralities ofnetwork elements 520 ₁-520 _(N) (collectively, network elements 520),and management system 540.

As depicted in FIG. 5, management system 540 generates a plurality ofSIP message prioritization policies 530 ₁-530 _(N) (collectively, SIPmessage prioritization policies 530). As depicted in FIG. 1, one or moreof SIP message prioritization policies may be distributed to each of theprioritizing SIP network elements 510 (illustratively, SIP messageprioritization policy 530 ₁ is distributed to prioritizing SIP networkelement 510 ₁, SIP message prioritization policy 530 ₂ is distributed toprioritizing SIP network element 510 ₂, and SIP message prioritizationpolicy 530 _(N) is distributed to prioritizing SIP network elements 510₂ and 510 ₃. Although omitted for purposes of clarity, in oneembodiment, one or more of the SIP message prioritization policies 530may be distributed to various other network elements (e.g., networkelements 502, network elements 520, and the like, as well as variouscombinations thereof.

As depicted in FIG. 5, prioritizing SIP network elements 510 ₁-510 _(N)receive incoming SIP messages from pluralities of network elements 502₁-502 _(N), respectively. As depicted in FIG. 2, prioritizing SIPnetwork elements 510 ₁-510 _(N) receive incoming SIP messages frompluralities of network elements 502 ₁-502 _(N), respectively. In oneembodiment, network elements 502 may include SIP UAs, non-prioritizingand prioritizing SIP network elements, non-SIP network elements (e.g.,routers), and the like, as well as various combinations thereof.Although depicted and described as distinct pluralities of networkelements, at least a portion of the network elements of respectivepluralities of network elements 502 may be the same (e.g., at least aportion of the network elements may be common to network elements 502 ₁,network elements 502 ₂, and the like). Although not depicted, at least aportion of prioritizing SIP network elements 510 may belong to one ormore of the pluralities of network elements 502 such that exchanging ofmessages between prioritizing SIP network elements 510 is supported.

As depicted in FIG. 5, prioritizing SIP network elements 510 ₁-510 _(N)transmit outgoing SIP messages to various combinations of networkelements 520. As depicted in FIG. 2, prioritizing SIP network element510 ₁ transmits outgoing SIP messages to network elements 520 ₁ and 520₂, prioritizing SIP network element 510 ₂ transmits outgoing SIPmessages to network elements 520 ₃ and 520 ₄, and prioritizing SIPnetwork element 510 _(N) transmits outgoing SIP messages to networkelements 520 ₄ and 520 _(N). In one embodiment, network elements 520 mayinclude SIP UAs, non-prioritizing and prioritizing SIP network elements,non-SIP network elements (e.g., routers), and the like, as well asvarious combinations thereof. Although depicted and described asdistinct network elements, at least a portion of network elements 520may be other network elements depicted and described herein (e.g.,network element 520 ₃ may represent a prioritizing SIP network elementsuch as prioritizing SIP network element 510 _(N) such that prioritizingSIP network element 510 ₂ transmits outgoing SIP messages toprioritizing SIP network element 510 _(N).

As depicted in FIG. 5, network elements 502 transmit SIP messages toprioritizing SIP network elements 510 and prioritizing SIP networkelements transmit SIP messages to network elements 520. Since, asdepicted in FIG. 1, various combinations of SIP network elements andnon-SIP network elements may communicate in various differentconfigurations in order to provide SIP message prioritization betweennetwork elements (e.g., over at least a portion of an end-to-end pathbetween a SIP UAC and a SIP UAS), the present invention is not intendedto be limited by prioritization architecture 500 of FIG. 5. Although notdepicted as communicating (for purposes of clarity in describingfunctions associated with prioritizing SIP network elements), asdescribed herein, various combinations of prioritizing SIP networkelements 510 may communicate for propagating message priority levels ofSIP messages between network elements.

As depicted in FIG. 5, prioritizing SIP network element 510 includes aparsing module 512, a prioritizing module 514, and a parsing andprocessing module 516. Although depicted and described as includingspecific parsing, prioritizing, and processing modules, as describedherein with respect to FIG. 3, in other embodiments, parsing module 512and prioritizing module 514 may be implemented as a single module,parsing and processing module 516 may be implemented using a pluralityof modules (e.g., a parsing module for parsing previously unparsedportions of the SIP message header and SIP content), and the like, aswell as various combinations thereof. Although not depicted,prioritizing SIP network elements 510 ₂-510 _(N) may include modulessimilar to parsing module 512, a prioritizing module 514, and a parsingand processing module 516 depicted and described herein with respect toSIP prioritizing network element 510 ₁.

The parsing module 512 receives incoming SIP messages (eithernon-prioritized or prioritized) from network elements 502 ₁. The parsingmodule 512 parses incoming SIP messages to obtain SIP messageprioritization information for use in prioritizing the incoming SIPmessages (i.e., information for use in determining respective messagepriority levels for the SIP messages and assigning the determinedmessage priority levels to the SIP messages). The prioritizing module514 prioritizes SIP messages using SIP message prioritization policy 530received from management system 540 and SIP message prioritizationinformation received from parsing module 512. As depicted in FIG. 5,prioritizing module 514 may discard/reject a portion of the SIP messages(e.g., in response to detected load conditions and based on assignedmessage priority levels, SIP message prioritization policy 530, and thelike, as well as various combinations thereof). The prioritizing module514 passes the remaining prioritized SIP message to parsing andprocessing module 516.

As depicted in FIG. 5, parsing and processing module 516 parses theprioritized SIP messages (e.g., parses portions of each prioritized SIPmessage not parsed by parsing module 512). The parsing and processingmodule 516 processes the prioritized SIP messages. In one embodiment,parsing and processing module 516 processes prioritized SIP messagesaccording to the respective assigned message priority levels. Althoughnot depicted, in one embodiment, parsing and/or processing of SIPmessages may be performed according to SIP message prioritization policy530. The processed SIP messages are transmitted from prioritizing SIPnetwork element 510 to network elements 520). In one embodiment,processed SIP messages are transmitted from prioritizing SIP networkelement 510 to network elements 520 in a manner for propagatingrespective assigned message priority levels of the SIP messages.

As depicted in FIG. 5, and described herein, SIP message prioritizationpolicies 530 may be updated. In one embodiment, SIP messageprioritization policies 530 may be updated by management system 540. Inone embodiment, SIP message prioritization policies 530 may be updatedby prioritizing SIP network elements 510 (e.g., by prioritizing SIPnetwork elements 510 to which the SIP message prioritization policies530 are distributed, respectively). In one embodiment, prioritizing SIPnetwork elements 510 may update the SIP message prioritization policies530 either locally on prioritizing SIP networks 510, respectively, orremotely on management system 140 (i.e., by transmitting SIP messageprioritization feedback information to management system 140). In oneembodiment, SIP message prioritization policies 530 may be updated byvarious other network elements (e.g., network elements 502, networkelements 520, and the like), various other management systems (notdepicted), and the like, as well as various combinations thereof.

In one embodiment, SIP message prioritization policies 530 may beupdated using information from parsing and processing modules 516 ofrespective prioritizing SIP network elements 510 to which the SIPmessage prioritization policies 530 are distributed, respectively. Insuch embodiments, information provided by parsing and processing modules516 may include at least one of information obtained from SIP messageparsing, results of SIP message processing, and the like, as well asvarious combinations thereof. For example, in one embodiment, suchinformation may include changes in at least one of traffic volume,volumes of different message types, Volumes of messages from/to specificsource/destination addresses, average message sizes, and the like, aswell as various combinations thereof.

In one embodiment, one or more of SIP message prioritization policies530 may be updated in response to various information, conditions, andthe like, as well as various combinations thereof. In one embodiment, aSIP message prioritization policy may be updated in response to an eventknown, expected, or predicted to result in changes to traffic volumes(e.g., to support increased network traffic resulting from a televisionprogram, a webcast event, and the like, as well as various combinationsthereof. In one embodiment, a SIP message prioritization policy may beupdated in response to availability of a new service. In one embodiment,the SIP message prioritization policy may be updated in response toaddition of a customer, deletion of a customer, changes in customersize, and the like, as well as various combinations thereof.

In one embodiment, a SIP message prioritization policy may be updated inresponse to actual traffic conditions detected within the network. Forexample, various planned and unplanned events may result in significantincreases in traffic to particular websites, significant increases inemergency traffic, and the like, as well as various other increases anddecreases in traffic to specific addresses, increases and decreases inspecific types of traffic, and the like, as well as various combinationsthereof. In one embodiment, such dynamic traffic changes may be reportedfrom the network (e.g., reported and/or retrieved from SIP networkelements, routers, traffic monitoring devices, and the like, as well asvarious combinations thereof) for use by a management system todynamically update SIP message prioritization policies which may then bedistributed to the network for use in reacting to such dynamic trafficchanges. In one embodiment, such dynamic traffic changes may be reporteddirectly to a prioritization policy management system (illustratively,management system 540), to a traffic load monitoring system incommunication with a prioritization policy management system, and thelike, as well as various combinations thereof.

FIG. 6 depicts a high-level block diagram of a general-purpose computersuitable for use in performing the functions described herein. Asdepicted in FIG. 6, system 600 comprises a processor element 602 (e.g.,a CPU), a memory 604, e.g., random access memory (RAM) and/or read onlymemory (ROM), a SIP message prioritization module 605, and variousinput/output devices 606 (e.g., storage devices, including but notlimited to, a tape drive, a floppy drive, a hard disk drive or a compactdisk drive, a receiver, a transmitter, a speaker, a display, an outputport, and a user input device (such as a keyboard, a keypad, a mouse,and the like)).

It should be noted that the present invention may be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a general purposecomputer or any other hardware equivalents. In one embodiment, thepresent SIP message prioritization module or process 605 can be loadedinto memory 604 and executed by processor 602 to implement the functionsas discussed above. As such, SIP message prioritization process 605(including associated data structures) of the present invention can bestored on a computer readable medium or carrier, e.g., RAM memory,magnetic or optical drive or diskette and the like.

Although primarily depicted and described herein with respect to SIPmessage prioritization, in one embodiment, the present invention maysupport prioritization of other non-SIP message types (e.g., HTTPmessages). In such embodiments, prioritization of other message typesmay include prioritization of other message types within a networkelement for controlling processing of messages within a network element,prioritization of other messages over at least a portion of anend-to-end communication path, and the like, as well as variouscombinations thereof. Although primarily depicted and described hereinwith respect to message prioritization, in one embodiment, the presentinvention may be adapted for supporting prioritization for various otherforms of information.

Although primarily depicted and described herein with respect to ageneric SIP-based communication network, in one embodiment, at least aportion of service provider domain 101 operates as an IP MultimediaSubsystem (IMS) network architecture as standardized by Third GenerationPartnership Project (3GPP) and Third Generation Partnership Project Two(3GPP2). In the IMS network architecture, SIP signaling (control) andassociated media sessions (data) are separated such that SIP signalingis used to support services such as voice-over-IP sessions, multimediasessions, presence, instant messaging, and the like. Although primarilydepicted and described herein with respect to supporting signalingbetween generic SIP network elements, SIP may be used to supportsignaling between IMS-specific network elements, such as call sessioncontrol functions (e.g., proxy call session control functions (P-CSCFs),interrogating call session control functions (I-CSCFs), serving callsession control functions (S-CSCFs), and the like, as well as variouscombinations thereof).

Although various embodiments which incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings.

1. A method for handling a SIP message at a network node, comprising:determining a message priority level for the SIP message; andpropagating the SIP message from the network node based on the messagepriority level of the SIP message, wherein propagating the SIP messagefrom the network node based on the message priority level comprises:selecting one of a plurality of output ports of the network node basedon the message priority level; and propagating the SIP message from thenetwork node using the selected output port.
 2. A method for handling aSIP message at a network node, comprising: determining a messagepriority level for the SIP message; and propagating the SIP message fromthe network node based on the message priority level of the SIP message,wherein propagating the SIP message from the network node based on themessage priority level comprises: selecting one of a plurality of outputnetworks available from the network node based on the message prioritylevel; and propagating the SIP message from the network node toward theselected output network.
 3. The method of claim 2, wherein the outputnetworks comprise IP networks supporting different quality-of-servicelevels.
 4. A method for handling a SIP message at a network node,comprising: determining a message priority level for the SIP message;and propagating the SIP message from the network node based on themessage priority level of the SIP message, wherein propagating the SIPmessage from the network node based on the message priority levelcomprises: selecting one of a plurality of input ports associated withat least one network element based on the message priority level; andpropagating the SIP message from the network element toward the selectedinput port.
 5. The method of claim 4, wherein the plurality of inputports are associated with at least two network elements.
 6. An apparatusfor handling a SIP message at a network node, comprising: means fordetermining a message priority level for the SIP message; and means forpropagating the SIP message from the network node based on the messagepriority level of the SIP message, wherein the means for propagating theSIP message from the network node based on the message priority levelcomprises: means for selecting one of a plurality of output ports of thenetwork node based on the message priority level; and means forpropagating the SIP message from the network node using the selectedoutput port.
 7. An apparatus for handling a SIP message at a networknode, comprising: means for determining a message priority level for theSIP message; and means for propagating the SIP message from the networknode based on the message priority level of the SIP message, wherein themeans for propagating the SIP message from the network node based on themessage priority level comprises: means for selecting one of a pluralityof output networks available from the network node based on the messagepriority level; and means for propagating the SIP message from thenetwork node toward the selected output network.
 8. The apparatus ofclaim 7, wherein the output networks comprise IP networks supportingdifferent quality-of-service levels.
 9. An apparatus for handling a SIPmessage at a network node, comprising: means for determining a messagepriority level for the SIP message; and means for propagating the SIPmessage from the network node based on the message priority level of theSIP message, wherein the means for propagating the SIP message from thenetwork node based on the message priority level comprises: means forselecting one of a plurality of input ports associated with at least onenetwork element based on the message priority level; and means forpropagating the SIP message from the network element toward the selectedinput port.
 10. The apparatus of claim 9, wherein the plurality of inputports are associated with at least two network elements.